Tool holder, and chisel support and drilling bit for a drill head

ABSTRACT

A drill head including a tool holder, chisel supports mounted thereon and drill bits. According to this invention, the chisel supports can be separated from the tool holder.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a tool holder for a drill head with afastening shank through which a mud channel passes and with a supportstructure fastened directly or indirectly to the fastening shank.

This invention also relates to a drill bit support for a drill head,with a support head on which a bearing section of a drill bit that canbe fastened in rotary fashion.

This invention also relates to a drill bit for rotary attachment to adrill bit support.

2. Discussion of Related Art

Drill heads are used to dig drilling holes in the ground forconstruction projects. To do so, the drill heads are fastened at one endto a drill pipe. The rotation and the advancing motion of a drive unitare transferred to the drill head by the drill pipe.

For example, horizontal drilling machines are known, which are used toproduce a relatively horizontal bore in the ground. This is done todrive the drill head under roads, buildings, or the like. Usually, thedrill heads have a tool holder that holds drill bits, which aresupported in sockets in rotary fashion. When the drill head is driventhrough the ground, the drill bits roll against the material to beremoved and break it free. This causes it to fragment so that it can beflushed away with a mud emulsion. The mud emulsion is supplied to thedrill heads via the drill pipe. The drill heads are subject to wear andthus must be regularly replaced.

SUMMARY OF THE INVENTION

One object of this invention is to provide a drill bit support and adrill bit, which are designed so that they are optimized with regard towear.

This object and others of this invention relating to the tool holder areattained if the support structure has tool sockets offset from oneanother in the circumference direction for accommodating drill bitsupports in a replaceable fashion.

According to this invention, there is a wear system in which the toolholder has an interface for the replaceable coupling of the drill bitsupport. Consequently, the tool holders and the drill bit supports canbe replaced independently of one another in accordance with their wearstate. This achieves an optimization of the service life of theindividual tool components.

According to one embodiment of this invention, it is possible for thetool sockets to be embodied or shaped in the form of insertion sockets.Thus, the drill bit supports can be easily changed and preciselypositioned, even in the rough conditions of worksite operations and ininstallation situations with limited accessibility.

In this connection, it is particularly advantageous if the tool socketshave an insertion opening, which opens in the direction oriented awayfrom the fastening shank or in a radially outward direction. Thus, thedrill bit supports can be inserted into the insertion sockets from thefront side or the rear side of the drill head. Alternatively, theinsertion socket can also be embodied or shaped in the form of a guideprojection onto which the drill bit support can be slid.

A tool holder according to this invention can be embodied or formed sothat in the region of the tool socket, a fastening receptacle, inparticular a screw receptacle, is provided, which opens in the directiontoward the fastening shank and is accessible from there. Thus, the screwreceptacle is oriented so that the screw head of a fastening screw isinserted into the screw receptacle and is favorably positioned withregard to wear. In particular, it is then not exposed to the abrasivewear action.

A possibility for exact positioning of the drill bit supports isprovided in a simple way if the tool sockets have two guide grooves orguides situated on opposite sides from each other.

Thus, a favorable centering is achieved if the guide grooves arelaterally delimited by two flanks, which extend in the longitudinaldirection of the groove and are oriented at an angle relative to eachother. This design is also load-optimized. The wall sections of the toolsockets that form the grooves become thicker in the direction toward thebottom of the groove and thus have a large load cross-section at thelocation in which the highest loads occur.

Preferably, the tool sockets each at least partially comprises two guideprojections and outlet channels formed between the guide projections ofadjacent tool sockets. The rock material that is removed with thesupplied emulsion can be conveyed away via the outlet channels.

One object of this invention relating to the drill bit support isachieved if an insertion lug is directly or indirectly coupled to thesupport head of the drill bit support. With this insertion lug, thedrill bit support can be inserted into a correspondingly embodied toolsocket of the tool holder. It can then be replaced independently of thetool holder, each as a function of its individual wear state. Thisachieves a wear-optimized design. With its insertion lug, the drill bitsupport can be quickly and simply attached to the tool holder anddetached from it again.

The insertion lug can have guide pieces on two opposing sides. Withthese guide pieces, it can be inserted, for example, into grooves of thetool holder, in order to thus achieve a reliable and exact positioning.

For a load-optimized design, the guide pieces can have two guidesurfaces that are oriented at an angle relative to each other and areconnected to each other via a connecting section. The guide pieces widenout starting from their free ends and thus have their maximumcross-section in the region in which they connect to the drill bitsupport and therefore have a load-optimized design.

In one embodiment of this invention, the insertion lug has a support lugat its free end and this support lug produces an additional stableattachment.

For example, it is also possible for the support lug to transition intothe guide pieces in a way that results in an easy-to-produce geometry.

A drill bit support according to this invention can also be embodied sothat the insertion lug is delimited by a convex inner surface and/or aconvex outer surface. In the region of the convex inner surface, thedrill bit support can correlate with a correspondingly concave recess ofthe tool holder. The matching convex/concave regions in the vicinity ofthe inner surface produce an interface, which, like a key in a lock,promotes the association of the correct drill bit support with a toolholder. The convex outer surface of the drill bit support reduces thenumber of possible weak points of the bore wall and thus contributes toa wear-optimized layout of the tool design. The convex shape alsoachieves a thickening of the insertion lug cross-section and thus agreater stability.

A drill bit support according to this invention can have a support headthat supports a bearing section and labyrinth seal parts are positionedor situated in the transition region from the support head to thebearing section. These labyrinth seal parts can be put together withcorresponding labyrinth seal parts of a drill bit in order to thusproduce a labyrinth seal. This labyrinth seal counteracts thepenetration of rock material and thus protects the bearing section and abearing contained therein.

A drill bit can be simply affixed to a drill bit support so that thebearing section has a circumferential groove for accommodating aclamping element. The clamping element can then be connected to thedrill head with form-locking engagement and/or frictional, nonpositiveengagement.

In one embodiment according to this invention, the central longitudinalaxis formed by the bearing section extends at an angle in the rangebetween 30° and 90° in relation to the outer surface. This achieves anoptimization of the bearing pressure on the bearing between the drillbit and the tool support. It is advantageous for this angular range tolie between 50° and 70°. This also produces an outer surface of thedrilling tool that is functional and easy to shape.

One object of this invention is also achieved with a drill bit forcoupling to a drill bit support in rotary fashion. The drill bit has anouter surface with hard material elements. The drill bit also has abearing receptacle. In the region of the bearing receptacle, the drillbit according to this invention has labyrinth seal parts, which can beput together with labyrinth seal parts of the drill bit support to forma labyrinth seal. This labyrinth seal counteracts the penetration ofrock material, thus using simple means to effectively protect thebearing receptacle from wearing action.

In order to also maintain a reliable position-fixing relative to thedrill bit support, even when there are abrupt and uneven loads on thedrill bit, it is possible according to this invention for the bearingreceptacle to have an end surface that supports a support element ofhard material. This support element can cooperate with a counterpartsupport element or a counterpart surface of the drill bit support.

BRIEF DESCRIPTION OF THE DRAWINGS

This invention is explained in greater detail below in view of anexemplary embodiment shown in the drawings, wherein:

FIG. 1 is a perspective side view of a drill head with a tool holderand, mounted thereon, drill bit supports with drill bits;

FIG. 2 is a partial section view taken through the drill head accordingto FIG. 1;

FIG. 3 is a perspective front view of a drill bit support;

FIG. 4 is a perspective front view of a drill bit support with drillbits mounted thereon;

FIG. 5 is a sectional detail view taken along line V-V in FIG. 2;

FIG. 6 is a perspective side view of another embodiment of a drill headwith a tool holder and, mounted thereon, drill bit supports with drillbits;

FIG. 7 is a partial section view taken through the drill head accordingto FIG. 6;

FIG. 8 is a perspective front view of a drill bit support;

FIG. 9 is a sectional detail view taken along line IX-IX in FIG. 7;

FIG. 10 is a full section view taken through the drill bit supportaccording to FIG. 8.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a drill head with a tool holder 10 having a base part as asupport structure 12. The support structure 12 has a downward-pointingfastening shank 11 integrally formed onto it. The fastening shank 11 hasa conical external thread. The support structure 12 has three toolsockets 13, which protrude from the outside of the support structure 12and are offset from one another by 120° and are embodied in the form ofpockets.

FIG. 5 shows one embodiment of the tool sockets 13 in greater detail. Asshown, each tool socket 13 has two guide projections 13.1 on theoutside. The guide projections 13.1 each is provided with or has arespective guide groove 13.2, the guide grooves 13.2 of a tool socket 13are situated on opposite sides from each other. The guide grooves 13.2are delimited laterally by flanks 13.3 that are oriented at an anglewith respect to each other, preferably in the range between 80° and100°. This angular range ensures a reliable and jam-free function of theguide. The two guide projections 13.1 form convex surfaces on theoutside, which lie along a pitch circle, as shown in FIG. 5.

FIG. 1 shows that in the region of the fastening shank 11, the guideprojections 13.1 are connected by a transition section that is providedwith or has a screw receptacle 12.1, as shown in FIG. 2. The screwreceptacle 12.1 serves to accommodate a fastening screw 12.2. The screwreceptacle 12.1 is let into the support structure 12 so that it feedsinto the tool socket 13 and so that it is oriented toward the free endof the fastening shank 11. In this way, the head of the fastening screw12.2 is accommodated in a protected way, on the side oriented away fromthe advancing direction of the drill head. The support structure 12, asshown in FIG. 2, has a mud channel 15 passing through it. The mudchannel 15 feeds into a nozzle. The nozzle 15.1 transitions into achannel chamber 14, which feeds into the outlet channels 14.1. Theoutlet channels 14.1 are each situated between the guide projections13.1 of adjacent tool sockets 13.

Drill bit supports 20 can be mounted in the tool sockets 13. The designof the drill bit support 20 is shown in greater detail in FIG. 3. Asshown, the drill bit support 20 has an insertion lug 21 that terminateswith an inner surface 24 and on the outside, with a convex outer surface25. Rib-like guide pieces 22 are integrally formed onto the sides of theinsertion lug 21. The guide pieces 22 have two guide surfaces 22.1oriented at an angle with respect to each other so that the guide pieces22 taper from their connecting region to the insertion lug 21 towardtheir free end. The inclination angle is selected in accordance with theangle between the flanks 13.3. The guide surfaces 22.1 transition intoone another via a connecting section 22.2. In the region of or near thefree end of the insertion lug 21, a support lug 23 is formed, which isembodied as a transition section and, like the guide pieces 22, isembodied as rib-like. The support lug 23 transitions flush into theguide pieces 22 and thus has the same cross-sectional geometry.Consequently, it has guide surfaces 23.1 inclined in relation to eachother and in turn connected to each other by a connecting section.

The insertion lug 21 has a support head 26 with a bearing section 26.3formed integrally onto it. In the transition region to the bearingsection 26.3, the support head 26 has an annular shoulder 26.1 extendingaround it, which is adjoined by a circumferential groove 26.2. Theshoulder 26.1 and the groove 26.2 constitute or form labyrinth sealparts. The cylindrical bearing section 26.1 is first adjoined by aconcave transition 26.4 in order to adapt its size to a reduced-diameterconnector piece at the end. A circumferential groove 26.5 isincorporated into the connector piece. The bearing section 26.3terminates at its end with an end surface 26.7. As shown in FIG. 2, theend surface 26.7 has a recess incorporated into it, into which a supportelement 26.6, composed of or comprised of a hard material such as a hardmetal, is soldered, glued, or press-fitted. FIG. 2 also shows that anannular clamping element 29.1 in the form of a round wire snap ring issnapped into the circumferential groove 26.2.

FIGS. 2 and 4 show that a drill bit 30 can be connected to the drill bitsupport 20. The drill bit 30 has an outer surface 31 with at least onecircumferential groove 32, 33. Hard material elements 34, in particularhard metal elements, can be soldered into holes on the outer surface 31.The drill bit 30 has an internal bearing receptacle 37 that is embodiedor shaped in the form of a hole in the drill bit 30. The bearingreceptacle 37 transitions via a diameter reduction into a blind holebore that is equipped with or has a groove 38. The blind hole boreterminates with an end surface, in which a recess for a support element39 is provided. The support element 39 can be composed of or comprisedof a hard material such as hard metal. In the end region of the bearingreceptacle 37, the drill bit 30 is provided with or has acircumferential groove 35 and an adjoining circumferential shoulder 36.The groove 35 and the shoulder 36 are labyrinth seal parts. To mount thedrill bit 30 on the drill bit support 20, a bearing 29 is inserted intothe bearing receptacle 37 of the drill bit 30 and slid onto the bearingsection 26.3 of the drill bit support 20. The bearing 29 in thisembodiment is formed as a needle bearing, making it possible to achievea small overall height.

As shown in FIG. 2, a radial shaft sealing ring or a similarcircumferential seal 28 is also inserted in the region between thebearing receptacle 37 and the bearing section 26.3. In the insertedstate, the circumferential shoulder 36 of the drill bit 30 protrudesinto the circumferential groove 26.2 of the drill bit support 20. In asimilar way, the circumferential shoulder 26.1 of the drill bit support20 protrudes into the circumferential groove 35 of the drill bit 30, sothat a labyrinth seal is formed. Consequently, the circumferentialshoulders 36 and 26.1 and the grooves 26.1 and 35 constitute formed-onseal profiles or labyrinth profiles. Adjacent to the labyrinth seal, theseal 28 seals the bearing receptacle 37 so that the labyrinth seal andthe seal 28, effectively protect the bearing 29 from the penetration ofrock material and mud emulsion. This prevents premature failure of thebearing 29. In order to affix the drill bit 30 to the drill bit support20, the clamping element 29.1 simultaneously engages in the grooves 26.5and 38 of both the drill bit support 20 and the drill bit 30. Thisproduces a form-locked engagement between these components. In addition,the drill bit 30 is supported with its support element 39 on the supportelement 26.6 of the drill bit support 20. During assembly of the drillbit 30, the clamping element 29.1 slides between the bearing receptacle37 and the region of the bore that accommodates the groove 38. As aresult, the clamping element 29.1 is compressed radially inward into thegroove 26.2 and its diameter is reduced. The clamping element 29.1 canthen snap into the groove 38 so that a form-locked connection isachieved.

The tool combination composed of the drill bit support 20 and drill bit30 can be inserted into a tool socket 13 of the tool holder 10. For thispurpose, the insertion lug 21 is slid into the tool socket 13, which isembodied or shaped in the form of an insertion socket. In the process ofthis, the guide surfaces 22.1 of the guide pieces 22 slide along theflanks 13.3 of the guide grooves 13.2. The insertion movement of thedrill bit support 20 is limited by the support surfaces 23.2 that cometo rest against corresponding counterpart surfaces of the tool sockets13. Then the fastening screw 12.2 can be inserted through the screwreceptacle 12.1 and screwed into a threaded hole 21.1 of the insertionlug 21. FIG. 5 shows the joined pair of the insertion lug 21 and thetool socket 13. As this drawing shows, the guide surfaces 22.1 restagainst the flanks 13.3. The convex outer surface 25 of the insertionlug 21 transitions flush into the convex outer sections of the guideprojections 13.1, thus avoiding an abrupt cross-sectional change infavor of a tool design that is optimized in terms of wear.

As shown in FIG. 5, the guide projections 13.1 are spaced farther apartfrom the outer surface 25 than from the inner surface 24, which isillustrated in FIG. 5 with the dimensions a and b, where a is smallerthan b. Correspondingly, there is a certain wear volume available in theregion of or near the outer surface of the insertion lug 21, which canwear down during use of the tool without significantly influencing thefastening region between the insertion lug 21 and the tool socket 13.The cross-section of the insertion lug 21 is thus asymmetrical to itscentral transverse plane Q extending in the longitudinal direction ofthe insertion lug. Consequently, the tool sockets 13 are alsoasymmetrical.

After all three drill bit supports 20 are fastened to the tool holder10, the drill head is ready for use. During engagement of the tool, thetool holder 10 and with it, the drill bit support 20, rotates around therotation axis R. As this occurs, the drill bits 30 come into engagementwith the material to be removed. Because of the rotating motion, thedrill bits 30 roll in the drilling hole and the hard material elements34 cut into the material to be removed. An emulsion is supplied via themud channel 15, which is sprayed out in the region of the nozzle 15.1.The emulsion flushes out the removed and crushed material, where theemulsion then flows out via the outlet channels 14.1. The drill bits 30are designed differently from one another in the region of or near theirouter surface 31 so that the rotating rows of hard material elements 34of one drill bit 30 can travel in a respective groove 32, 33 of theadjacent drill bit 30.

During engagement of the tool, the above-described tool combinationexperiences wear. Consequently, the drill bit 30, the drill bit support20, and the tool holder 10 undergo continuous wear. Depending on thewear state, according to this invention, the tool holder 10, the drillbit support 20, and the drill bits 30 can each be individually replaced.For tool replacement, the drill head is detached from the drillinglance. To accomplish this, the screw connection between the fasteningshank 11 and the drilling lance is disconnected. The drill bit support20 can then be detached by simply unscrewing the fastening screw 12.2from the tool holder 10. The drill bit 30 can be pressed out from thedrill bit support 20. In the course of this, the clamping element 29.1,due to the geometry of the grooves 26.5 and 35, is deflected radiallyinward and thus disengages from the groove 35 of the drill bit 30. Thedrill bit 30 can then be slid off of the drill bit support 20.

FIGS. 6 through 10 show another embodiment of an apparatus according tothis invention. In it, parts that are the same have the same referencenumerals so that in order to avoid repetitions, reference can be made tothe descriptions above.

FIG. 6 shows a drill head with a tool holder 10, having the base part asa support structure 12. The support structure 12 has a downward-pointingfastening shank 11 integrally formed onto it. The fastening shank 11 hasa conical external thread. The support structure 12 is equipped with orhas three tool sockets 13, which protrude from the outside of thesupport structure 12 offset from one another by 120°.

FIG. 9 clearly shows the tool socket 13. As the drawing shows, thesupport structure 12 has one guide projection 13.1 for each tool socket13. Each guide projection 13.1 has longitudinal guides in the form ofprism guides on opposite sides. The two prism guides are each formed bytwo guide surfaces 22.1 oriented at an angle relative to each other. Anangle in the range between 45° and 75° between the guide surfaces 22.1can be advantageous. This makes it possible to ensure a simple assemblyin the rough conditions of worksite operations. In addition, thisembodiment of the guide projections 13.1 does not have a tendency tojam. The guide surfaces 22.1 extend in the longitudinal direction of theguides, as shown in FIG. 8 and FIG. 10. The drill bit supports 20 can befastened to the tool sockets 13.

As shown in FIGS. 8 and 10, the tool supports 20 have a tool head 26,which is integrally joined to an insertion lug 21. On a radial inside,the insertion lug 21 forms a recessed fastening receptacle. In thiscase, the fastening receptacle is open toward the radial inside and inthe downward direction, as shown in FIG. 3. The fastening receptacle isdelimited by flanks 13.3 that are oriented relative to each other inprism fashion. The flanks 13.3 are oriented relative to each other atthe same angle as the guide surfaces 22.1 so that the flanks 13.3 andthe guide surfaces 22.1 form sliding guides.

As shown in FIG. 9, the flanks 13.3 are part of guide pieces 22, thatdelimit the fastening receptacle toward the front and the back in theadvancing direction V. The guide pieces 22 each forms a respectiveshoulder 22.2, which supports one of the flanks 13.3 and which engagesin a form-locked way behind the guide projection 13.1. As a result, thedrill bit support 20 is not offset in the radial direction. Now, thedrill bit support 20 can only be slid in the guidance direction. The twoguide pieces 22 are connected to each other by a wall section 21.2. Inthe attachment region to the tool holder 12, the guide pieces 22terminate at inner surfaces 24 that are flush with each other and aresituated or positioned in one plane. The outside of the tool support 20is defined by an outer surface 25 which is divided into a plurality ofpartial surfaces. In the advancing direction, the outer surface 25 has afirst surface section 25.1 which transitions at an angle into adeflecting surface 25.2. The deflecting surface 25.2 is tilted in theopposite direction from the advancing direction V, as shown in FIGS. 8and 9. The deflecting surface 25.2 transitions via a clearing edge 25.6into a side surface 25.3. The clearing edge 25.6 extends essentially inthe direction of the central longitudinal axis of the drill bit support20. In the opposite direction from the advancing direction V, the sidesurface 25.3 transitions at the back into an open surface 25.4. Betweenthe side surface 25.3 and the open surface 25.4 there is also an edgeregion. The open surface 25.4 finally ends at a surface section 25.5,which like the surface section 25.1, transitions into the inner surface24.

As shown in FIG. 8 and in FIG. 10, a fastening receptacle 21.3 in theform of a bore that passes through the two guide pieces 22 is located inthe region of or near the insertion lug 21. In order to mount the drillbit support 20 on the tool holder 10, the flanks 13.3 of the drill bitsupport 20 in the region of or near its open underside are placed ontothe guide surfaces 22.1. Then, the insertion lug 21 of the drill bitsupport 20 is slid onto the guide projection 13.1 of the tool socket 13in the guide direction. The sliding-on movement is limited by a stop21.4 (see FIG. 10). The stop 21.4 here is likewise embodied or shaped inthe form of an internal prism in order to produce a form-lockedengagement. This cooperates with corresponding prism surfaces of theguide projection 13.1. In the installed state, the fastening receptacle21.3 is flush with a corresponding bore receptacle in the guideprojection 13.1. Then a corresponding fastening element such as a hollowdowel pin can be slid through the flush fastening receptacles 21.3 ofthe insertion lug 21 and of the guide projection 13.1. This prevents anoffset of the tool support 20 relative to the tool holder 10 in theguidance direction.

As shown in FIG. 9, the guide piece 22 toward the front in the advancingdirection V has a larger wear volume than the rear guide piece 22. FIG.9 also shows that the structural height of the front guide piece 22 inthe radial direction is greater than the structural height of the rearguide piece 22 (distance dimension d₂>d₁). Consequently, the clearingedge 25.6 lies on a different, namely larger, pitch circle or center ofthe circle on the rotation axis R than the edge region between the opensurface 25.4 and the side surface 25.3. The side surface 25.3 thus has awear-optimized geometry that decreases radially inward in the oppositedirection from the advancing direction V, as shown in FIG. 9.

The insertion lug 21 supports a tool head 26, which has a bearingsection 26.3 integrally formed onto it.

The embodiment of the tool head 26 and drill bit 30 is selected to besimilar or essentially identical to that of the embodiment according toFIGS. 1 through 5, so that reference can be made to the explanationsabove.

1. A tool holder (10) for a drill head with a fastening shank (11)having at least one mud channel (15) passing through or associated withthe at least one mud channel (15) and having a support structure (12)fastened directly or indirectly to the fastening shank (11), the toolholder (10) comprising the support structure (12) having tool sockets(13) offset from one another in a circumference direction.
 2. The toolholder (10) according to claim 1, wherein the tool sockets (13) areformed as insertion sockets.
 3. The tool holder (10) according to claim2, wherein the tool sockets (13) have an insertion opening which opensin a direction oriented away from the fastening shank (11) or in aradially outward direction and/or the tool socket (13) has a protrudingguide region (13.1) with guide surfaces.
 4. The tool holder (10)according to claim 3, wherein near the tool socket (13) a fasteningreceptacle (12.1) being a screw receptacle positioned which opens in adirection toward the fastening shank (11) and being accessible from theopening.
 5. The tool holder (10) according to claim 4, wherein the toolsockets (13) have guide grooves (13.2) on opposite sides from eachother.
 6. The tool holder (10) according to claim 5, wherein the guidegrooves (13.2) are each delimited by two flanks (13.3) which extend in alongitudinal direction of the groove.
 7. The tool holder (10) accordingto claim 6, wherein the tool sockets (13) each at least partiallycomprises two guide projections (13.1), and outlet channels (14.1) areformed between the guide projections (13.1) of the adjacent tool sockets(13).
 8. A drill bit support (20) for a drill head with a support head(26), on which a drill bit (30) can be fastened to a bearing section(26.3) in a rotary fashion, comprising an insertion lug (21) directly orindirectly coupled to the support head (26).
 9. The drill bit support(20) according to claim 8, wherein the insertion lug (21) has guidepieces (22) on two opposite sides.
 10. The drill bit support (20)according to claim 9, wherein the guide pieces (22) have two guidesurfaces (22.1), and flanks (13.3) oriented at an angle relative to eachother and connected to each other by a connecting section (22.2). 11.The drill bit support (20) according to claim 10, wherein the insertionlug (21) has a support lug (23) at a free end.
 12. The drill bit support(20) according to claim 11, wherein the support lug (23) transitionsinto the guide pieces (22).
 13. The drill bit support (20) according toclaim 12, wherein the insertion lug (21) is delimited by a flat innersurface (24) and/or by a convex outer surface (25).
 14. The drill bitsupport (20) according to claim 13, wherein the support head (26)supports a bearing section (26.3) and labyrinth seal parts arepositioned in a transition region from the support head (26) to thebearing section (26.3).
 15. The drill bit support (20) according toclaim 14, wherein the bearing section (26.3) has a circumferentialgroove (26.5) for accommodating a clamping element (29.1).
 16. The drillbit support (20) according to claim 15, wherein a central longitudinalaxis (ML) formed by the bearing section (26.3) is oriented at an angle(a) in a range between 70° and 90° relative to the outer surface (25).17. The drill bit support (20) according to claim 16, wherein the guidepieces (22) on the insertion lug (21) are asymmetrical relative to thecentral longitudinal plane (L) extending in the longitudinal directionof the insertion lug.
 18. A drill bit (30) for a rotatable coupling to adrill bit support (20), having an outer surface (31) with hard materialelements (34) and a bearing receptacle (37), the drill bit (30)comprising: near the bearing receptacle (37), a circumferential groove(38) accommodating a clamping element (29.1) adjustable between twoclamping positions.
 19. The drill bit (30) according to claim 18,wherein the labyrinth seal parts are positioned near the bearingreceptacle (37).
 20. The drill bit (30) according to claim 19, whereinthe bearing receptacle (37) has an end surface that supports a supportelement (39) of a hard material.
 21. The drill bit (30) according toclaim 18 for mounting on a tool support (20) according to claim
 8. 22.The tool holder (10) according to claim 1, wherein near the tool socket(13) a fastening receptacle (12.1) being a screw receptacle positionedwhich opens in a direction toward the fastening shank (11) and beingaccessible from the opening.
 23. The tool holder (10) according to claim1, wherein the tool sockets (13) have guide grooves (13.2) on oppositesides from each other.
 24. The tool holder (10) according to claim 1,wherein the tool sockets (13) each at least partially comprises twoguide projections (13.1), and outlet channels (14.1) are formed betweenthe guide projections (13.1) of the adjacent tool sockets (13).
 25. Thedrill bit support (20) according to claim 8, wherein the insertion lug(21) has a support lug (23) at a free end.
 26. The drill bit support(20) according to claim 8, wherein the insertion lug (21) is delimitedby a flat inner surface (24) and/or by a convex outer surface (25). 27.The drill bit support (20) according to claim 8, wherein the supporthead (26) supports a bearing section (26.3) and labyrinth seal parts arepositioned in a transition region from the support head (26) to thebearing section (26.3).
 28. The drill bit support (20) according toclaim 8, wherein the bearing section (26.3) has a circumferential groove(26.5) for accommodating a clamping element (29.1).
 29. The drill bitsupport (20) according to claim 13, wherein a central longitudinal axis(ML) formed by the bearing section (26.3) is oriented at an angle (a) ina range between 70° and 90° relative to the outer surface (25).
 30. Thedrill bit support (20) according to claim 8, wherein the guide pieces(22) on the insertion lug (21) are asymmetrical relative to the centrallongitudinal plane (L) extending in the longitudinal direction of theinsertion lug.
 31. The drill bit (30) according to claim 18, wherein thebearing receptacle (37) has an end surface that supports a supportelement (39) of a hard material.